Tried switching graphics card, now machine won't post

[grievent]

MSI 770-C45 AM3 AMD 770 ATX AMD Motherboard
OCZ ModXStream Pro 500W Modular High Performance Power Supply
XFX HD-577A-ZNFC Radeon HD 5770 (Juniper XT) 1GB 128-bit GDDR5 PCI Express 2.1 x16 - old video card
ASUS EAH6770/DI/1GD5 Radeon HD 6770 1GB 128-bit GDDR5 PCI Express 2.1 x16 - new video card
Replaced failing Radeon 5770 with Radeon 6770 and now it won't work.
Motherboard LEDs turn on, CPU and case fans turn on. Graphics card fan turns on and then keeps cycling faster-slower every five seconds or so. No signal through VGA or DVI.
The problem persists even when I put the old card back in.
Tried:
Unplugging and replugging everything
Reseating RAM
Resetting CMOD
Reseating both cards
Different cable from PSU to card
Dusting all components thoroughly
Any solutions or diagnostics on the issue?

 

[Deleted member 217926]

Can you try the new card in a different system? Rare but could be DOA since it looks like you have tried everything I can think of. Are you sure it was the graphics card that was failing and not a bad power supply?

Edit: After rereading it sounds very much like a bad power supply. OCZ is not really known for making quality PSUs.

 

[grievent]

Thank you for the reply.

Both my old card (failing but not dead) and new card experience the same effect, which leads me to believe the new card isn't necessarily DoA.

Video Memory Stress Test reported pages of errors on the old failing graphics card, which led me to believe it was the card itself.

The power supply in question is two years old, though, and has been in very constant use. Would that be a telling factor? I'm not sure of their average lifespans, or the lifespan of a gfx card. Would you happen to know? Do you have recommendations for a good brand of power supply to look into?

 

[darkguset]

Yes, I was wondering the same... how did you determine that it was your VGA that was failing? Since you put the new one in and then back the old and none of them work any more, it more sounds like a PSU problem. Not sure if it is a multirail, but if so, have you made sure you have distributed the power loads efficiently?
Also, if you have not done so, do the bare test... take everything off the case and plug in only the necessary components, then power one at a time. A short between the case/mobo could be causing all sorts of faults. That is why we take the motherboard out and sit it on something non-conductive, usually the box that it came in.

 

[Deleted member 217926]

Both a power supply and a graphics card should last for years. In my experience a power supply is more likely to die than a graphics card though especially if the card is not overclocked/overvolted. In fact you can count on a power supply to wear out over time but 2 years is no where near the average lifespan.

Try your computer with a different power supply if you can. If you do need to buy a new one then Corsair, Seasonic, PC Power and Cooling, XFX, Enermax, Silverstone and Antec are the brands that you can count on for pretty much any of their models to be top quality. Other brands do make high quality units but can be hit or miss depending on the models.

 

[rage33]

+1 ^

 

[grievent]

Unfortunately, a new power supply didn't fix the problem. Also, it persists even with the MB removed from the case. Does anyone have any other ideas as to what might be the problem?

 

[Deleted member 217926]

Very likely you have a motherboard going bad then.

 

[grievent]

Is there a good way to test the motherboard?